Reversi · Rules guide
Reversi rules: how to play Othello
The rules take a minute: place a disc, outflank a line, flip everything in between. This guide covers the setup, legal moves, passing, counting, and why the corners and the squares beside them decide almost every game.
The short answer
- Start with four discs in the centre: white on d4 and e5, black on d5 and e4. Black moves first.
- A legal move must outflank and flip at least one enemy disc along a straight line.
- If you have no legal move you pass; you may never pass voluntarily.
- The game ends when neither side can move, and the most discs wins.
- Corner discs can never be flipped, which is why the squares next to them are the worst on the board.
The board, the discs and the object
Reversi — sold as Othello since 1971 — is played on an 8×8 board with 64 discs that are black on one side and white on the other. You capture by outflanking: trap a line of enemy discs between your new disc and one you already own, and every disc in between flips to your colour. The player with more discs when the board fills wins.
- Starting position: four discs in the centre — white on d4 and e5, black on d5 and e4.
- Black moves first.
- Every move must flip at least one disc. If it flips nothing, it is not a legal move.
Outflanking: the only rule that matters
Place a disc so that, in a straight line — horizontal, vertical or diagonal — one or more enemy discs lie between it and another of your discs, with no gaps. Every enemy disc in that line flips.
The details that decide games
- A move flips in all directions it closes at once — up to eight lines from one disc.
- Discs only flip along closed lines. A line ending in an empty square flips nothing.
- Flipped discs do not chain: the flip stops at the disc of yours that closed the line.
- You may not pass voluntarily. If you have a legal move you must play it.
- If you have no legal move, you pass and your opponent plays again — sometimes several times in a row.
Ending the game and counting
The game ends when neither player can move — usually because the board is full, sometimes earlier when one colour has been wiped out or all remaining empty squares are unplayable.
Count the discs. More discs wins. A wipeout, where one player has no discs left at all, ends the game immediately.
Scoring conventions
- In tournament play the winner's score is often recorded as the disc difference (for example 40–24), and unfinished boards are credited to the winner.
- A tie at 32–32 is a draw.
Why corners decide everything
A disc in a corner can never be flipped: there is no square beyond it to close a line from. Corners are permanently yours, and the edges next to them become stable too.
The corollary is the first real piece of Othello strategy: the squares next to a corner are poison. Playing an X-square hands your opponent the corner more often than not, and once they have it, a whole edge and diagonal begin to stabilise in their favour.
Notation and getting started
Othello notation is simply the square: columns a–h, rows 1–8, so the four opening moves for Black
are d3, c4, f5 and e6 — all identical by
symmetry. A game is recorded as a string of squares, which is why Othello databases are so compact.
Named openings come from the shape of the first few moves: the Diagonal, Perpendicular and Parallel openings, then the named lines — Tiger, Rose, Buffalo, Cow, Heath — that fill the opening books.
Common questions
Is Othello the same as Reversi?
Almost. Othello, trademarked in 1971, fixes the starting position as the four central discs and standardises the rules. Nineteenth-century Reversi let players place the first four discs themselves and used slightly different conventions. Everyone today plays the Othello rules.
Can you pass in Othello?
Only when you have no legal move — and then you must. You can never pass voluntarily, which means running your opponent out of moves is itself a winning strategy.
Do discs flip in more than one direction?
Yes. A single move flips every line it closes, in all eight directions at once. That is why one move can turn a losing board into a winning one.
Why is having more discs early a bad thing?
Because your discs are your opponent's ammunition, and a large group usually means fewer legal moves for you. Strong players keep their count low until roughly ten moves from the end.
What are X-squares and C-squares?
The squares diagonally next to a corner (X) and beside it on the edge (C). Playing them usually lets your opponent take the corner, which is permanent.
What happens if the board is not full?
If neither player has a legal move the game ends there, and the discs are counted as they stand. In tournament scoring the remaining empty squares are usually credited to the winner.
Play Reversi free, right now
No sign-up, no download — it runs in your browser against the computer, a friend on the same device, or a friend online.